Light-emitting device, light-emitting element and method of manufacturing same

ABSTRACT

Provided are a light-emitting element and a light-emitting device, and methods of fabricating the same. The method of fabricating a light-emitting element includes forming a buffer layer on a substrate and forming photonic crystal patterns and a pad pattern on the buffer layer. Each of the pad pattern and the photonic crystal patterns are made of a metal material, and the pad pattern is physically connected to the photonic crystal patterns. Forming a light-emitting structure includes sequentially stacking a first conductive pattern of a first conductivity type, a light-emitting pattern, and a second conductive pattern of a second conductivity type on the buffer layer. And the method also includes forming a first electrode that is electrically connected to the first conductive pattern and forming a second electrode that is electrically connected to the second conductive pattern.

CROSS REFERENCE TO RELATED APPLICATION

This application claims priority from Korean Patent Application No.10-2008-0089441 filed on Sep. 10, 2008 in the Korean IntellectualProperty Office, the disclosure of which is incorporated herein byreference in its entirety.

FIELD

The present invention relates to a light emitting element, lightemitting device, and methods of making same.

BACKGROUND OF THE INVENTION

Light-emitting elements such as light-emitting diodes (LEDs) emit lightwhen electrons combine with holes. Light-emitting elements consume lowpower, have a long life, can be installed in a limited space, and areresistant to vibrations.

A light-emitting element may include a light-emitting structure in whicha GaN pattern of an n type, a light-emitting pattern, and a GaN patternof a p type are stacked. Light is generated in the light-emittingpattern when carriers (e.g., electrons) of the GaN pattern of the n typecombine with carriers (e.g., holes) of the GaN pattern of the p type.

A major challenge in the development of light-emitting elements is toimprove light extraction efficiency. Light extraction efficiency denotesthe proportion of light, which comes out of a light-emitting structure(into, for example, air or transparent resin that surrounds thelight-emitting structure), in light generated within the light-emittingelement. A light-emitting structure may have an optical refractive indexof approximately 2.2 to 3.8, air may have an optical refractive index of1, and transparent resin may have an optical refractive index ofapproximately 1.5.

For example, when a light-emitting structure has an optical refractiveindex of 3.4, a portion of light generated within the light-emittingstructure may come out of the light-emitting structure into air at acritical angle of approximately 17 degrees and into transparent resin ata critical angle of approximately 26 degrees.

In this case, the light extraction efficiency of the light-emittingstructure is approximately 2.2% when a portion of light generated withinthe light-emitting structure comes out of the light-emitting structureinto air, and the light extraction efficiency of the light-emittingstructure is approximately 4% when the portion of the light generatedwithin the light-emitting structure comes out of the light-emittingstructure into transparent resin. The other portion of the light isreflected by the surface of the light-emitting structure and trapped inthe light-emitting structure.

A light-emitting structure may be made of a material containingIn_(x)Al_(y)Ga_((1-x-y))N (0≦x≦1, 0≦y≦1). In order to develop alight-emitting element using In_(x)Al_(y)Ga_((1-x-y))N, it is importantto form In_(x)Al_(y)Ga_((1-x-y))N having a low defect density. Forexample, In_(x)Al_(y)Ga_((1-x-y))N may be grown on a sapphire substrate.However, when the sapphire substrate is defective,In_(x)Al_(y)Ga_((1-x-y))N grown from the sapphire substrate may also bedefective.

In addition, the entire region of a light-emitting pattern may notalways be used equally. That is, only part of the light-emitting patternmay be used depending on the design of a light-emitting element. Thus,electric current may flow only in a specific region of thelight-emitting pattern, and light may be emitted only from the specificregion in which electric current flows. Consequently, the amount oflight emitted may be reduced.

SUMMARY OF THE INVENTION

In accordance with aspects of the present invention, provided aremethods of fabricating a light-emitting element and a light-emittingdevice that have improved light extraction efficiency, have reduceddefect densities, and can emit an increased amount of light.

Aspects of the present invention also provide a light-emitting elementand a light-emitting device that have improved light extractionefficiency, have reduced defect densities, and can emit an increasedamount of light.

However, aspects of the present invention are not restricted to the oneset forth herein. The above and other aspects of the present inventionwill become more apparent to one of ordinary skill in the art to whichthe present invention pertains by referencing the detailed descriptionof the exemplary embodiments given below.

According to an aspect of the present invention, there is provided amethod of fabricating a light-emitting element. The method includes:forming a buffer layer on a substrate; forming photonic crystal patternsand a pad pattern on the buffer layer, each of the pad pattern and thephotonic crystal patterns being made of a metal material, includingphysically connecting the pad pattern to the photonic crystal patterns;forming a light-emitting structure, including sequentially stacking afirst conductive pattern of a first conductivity type, a light-emittingpattern, and a second conductive pattern of a second conductivity typeon the buffer layer; and forming a first electrode and electricallyconnecting the first electrode to the first conductive pattern andforming a second electrode and electrically connecting the secondelectrode to the second conductive pattern.

The method can include forming the photonic crystal patterns atsubstantially the same level as the pad pattern.

The photonic crystal patterns can be a plurality of repetitively formedpatterns, and an interval between every two adjacent ones of therepetitive patterns is λ/4 and light generated by the light-emittingstructure can have a wavelength of λ.

The photonic crystal patterns can be line patterns or mesh patterns.

The pad pattern can have a width of approximately 40 μm or less.

The second electrode can be formed on an upper surface and sidewalls ofthe light-emitting structure.

The forming of the light-emitting structure can comprise: sequentiallyforming a first conductive layer of the first conductivity type, alight-emitting layer, and a second conductive layer of the secondconductivity type on the buffer layer; and patterning the secondconductive layer, the light-emitting layer, and the first conductivelayer to complete the light-emitting structure comprising the secondconductive pattern, the light-emitting pattern, and the first conductivepattern. The first conductive pattern can be wider than the secondconductive pattern and the light-emitting pattern and the firstconductive pattern can have a protruding portion extending in a lateraldirection, and the pad pattern can be disposed under the protrudingportion of the first conductive pattern.

The forming of the first electrode can comprise: patterning part of theprotruding portion of the first conductive pattern to expose the padpattern; forming an ohmic layer on the exposed pad pattern; and formingthe first electrode on the ohmic layer.

The method can further comprise: forming an insulating layer on theupper surface and sidewalls of the light-emitting structure afterforming the light-emitting structure. The forming of the first electrodecan comprise: etching a portion of the insulating layer to form a firstopening that penetrates the insulating layer; etching a portion of thefirst conductive pattern to form a second opening that penetrates thefirst conductive pattern, the second opening being narrower than thefirst opening; forming an ohmic layer which at least partially fills thefirst opening and the second opening; and forming the first electrode onthe ohmic layer.

The method can include wet-etching the portion of the insulating layerto form the first opening, and dry-etching the portion of the firstconductive pattern to form the second opening.

The forming of the first electrode and the second electrode cancomprise: forming the second electrode on the light-emitting structureafter forming the light-emitting structure; bonding the substrate to aconductive substrate such that the second electrode is disposed betweenthe substrate and the conductive substrate; removing the substrate; andforming the first electrode on the buffer layer.

The forming of the first electrode on the buffer layer can comprise:etching a portion of the buffer layer to expose at least part of the padpattern; forming an ohmic layer on the exposed portion of the padpattern; and forming the first electrode on the ohmic layer.

The conductive substrate can have a larger surface area than thesubstrate.

According to aspects of the present invention, methods of fabricating alight-emitting device by using the above method are also provided.

According to another aspect of the present invention, there is provideda light-emitting element including: a buffer layer formed on asubstrate; photonic crystal patterns and a pad pattern formed on thebuffer layer, wherein each of the pad pattern and the photonic crystalpatterns is made of a metal material, and the pad pattern is physicallyconnected to the photonic crystal patterns; a light-emitting structureincludes a first conductive pattern of a first conductivity type, alight-emitting pattern, and a second conductive pattern of a secondconductivity type sequentially stacked on the buffer layer; a firstelectrode electrically connected to the first conductive pattern; and asecond electrode electrically connected to the second conductivepattern.

The photonic crystal patterns can be formed at substantially the samelevel as the pad pattern.

According to another aspect of the present invention, there is provideda light-emitting element including: a conductive substrate; a secondelectrode formed on the conductive substrate; a light-emitting structureincluding a first conductive pattern of a first conductivity type, alight-emitting pattern, and a second conductive pattern of a secondconductivity type sequentially stacked on the second electrode; photoniccrystal patterns and a pad pattern formed on the first conductivepattern, wherein each of the pad pattern and the photonic crystalpatterns is made of a metal material, and the pad pattern is physicallyconnected to the photonic crystal patterns; a buffer layer formed on thefirst conductive pattern having an opening that exposes at least part ofthe pad pattern; and a first electrode which is formed on the exposedportion of the pad pattern.

The photonic crystal patterns can be formed at substantially the samelevel as the pad pattern.

The photonic crystal patterns can be a plurality of repetitive patterns,and an interval between every two adjacent ones of the repetitivepatterns can be λ/4 when light generated by the light-emitting structurehas a wavelength of λ.

The pad pattern can have a width of approximately 40 μm or less.

The first conductive pattern can be wider than the second conductivepattern and the light-emitting pattern and the first conductive patterncan have a protruding portion extending in a lateral direction, and thepad pattern can be disposed under the protruding portion of the firstconductive pattern.

The light-emitting element can further comprise: an opening formed inthe protruding portion of the first conductive pattern that exposes thepad pattern; and an ohmic layer formed on the exposed pad pattern,wherein the first electrode is formed on the ohmic layer.

The light-emitting element can further comprise: an insulating layerformed on an upper surface and sidewalls of the light-emittingstructure; a first opening that penetrates the insulating layer; asecond opening that penetrates the first conductive pattern and that isnarrower than the first opening; and an ohmic layer that at leastpartially fills the first opening and the second opening, wherein thefirst electrode can be formed on the ohmic layer.

The second electrode can be bowl-shaped, and the light-emittingstructure can be disposed within the second electrode.

The second electrode can have a protrusion, the light-emitting structurecan be divided into a first side and a second side by the protrusion,the photonic crystal patterns of the first electrode can then bedisposed on the first side of the light-emitting structure, and the padpattern of the first electrode can then be disposed on the second sideof the light-emitting structure.

According to aspects of the present invention, there are providedvarious light-emitting devices including any one of the abovelight-emitting elements.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other aspects and features of the present invention willbecome more apparent by describing in detail exemplary embodiments inaccordance therewith with reference to the attached drawings, in which:

FIGS. 1 through 9 are views for explaining a first exemplary embodimentof processes included in a method of fabricating a light-emittingelement according to aspects of the present invention;

FIGS. 10 through 14 are views for explaining a second exemplaryembodiment of processes included in a method of fabricating alight-emitting element according to aspects of the present invention;

FIGS. 15 through 19 are views for explaining a third exemplaryembodiment of processes included in a method of fabricating alight-emitting element according to aspects of the present invention;

FIG. 20 is a view for explaining a fourth exemplary embodiment of alight-emitting element according to aspects of the present invention;

FIG. 21A is a view for explaining a first exemplary embodiment of alight-emitting device according to aspects of the present invention;

FIG. 21B is a view for explaining a second exemplary embodiment of alight-emitting device according to aspects of the present invention;

FIG. 21C is a view for explaining a third exemplary embodiment of alight-emitting device according to aspects of the present invention;

FIG. 22 is a view for explaining a fourth exemplary embodiment of alight-emitting device according to aspects of the present invention;

FIG. 23 is a view for explaining a fifth exemplary embodiment of alight-emitting device according to aspects of the present invention;

FIG. 24 is a view for explaining a sixth exemplary embodiment of alight-emitting device according to aspects of the present invention;

FIG. 25 is a view for explaining a seventh exemplary embodiment of alight-emitting device according to aspects of the present invention;

FIGS. 26 through 28 are views for explaining an eighth exemplaryembodiment of a light-emitting device according to aspects of thepresent invention;

FIG. 29 is a view for explaining a ninth exemplary embodiment of alight-emitting device according to aspects of the present invention; and

FIGS. 30 through 33 are views for explaining tenth through thirteenthexemplary embodiments of light-emitting devices according to aspects ofthe present invention.

DETAILED DESCRIPTION

The present invention may be understood more readily by reference to thefollowing detailed description of exemplary embodiments in accordancetherewith and the accompanying drawings. The present invention may,however, be embodied in many different forms and should not be construedas being limited to the embodiments set forth herein. Like referencenumerals refer to like elements throughout the specification. In thedrawings, the size and relative size of the layers and regions areexaggerated for clarity.

It will be understood that when an element or layer is referred to asbeing “on” another element or layer, the element or layer can bedirectly on another element or layer or intervening elements or layers.In contrast, when an element or layer is referred to as being “directlyon” another element or layer, there are no intervening elements orlayers present. As used herein, the term “and/or” includes any and allcombinations of one or more of the associated listed items.

Spatially relative terms, such as “below,” “beneath,” “lower,” “above,”“upper,” and the like, may be used herein for ease of description todescribe the relationship of one element or component to anotherelement(s) or component(s) as illustrated in the figures. It will beunderstood that the spatially relative terms are intended to encompassdifferent orientations of the device in use or operation, in addition tothe orientation depicted in the figures. Throughout the specification,like reference numerals in the drawings denote like elements, and thustheir description will be omitted.

Embodiments in accordance with the invention are described herein withreference to plan and cross-section illustrations that are schematicillustrations of idealized embodiments. As such, variations from theshapes of the illustrations as a result, for example, of manufacturingtechniques and/or tolerances, are to be expected. Thus, embodimentsshould not be construed as limited to the particular shapes of regionsillustrated herein but are to include deviations in shapes that result,for example, from manufacturing. Thus, the regions illustrated in thefigures are schematic in nature and their shapes are not intended toillustrate the actual shape of a region of an element and are notintended to limit the scope of the invention.

FIGS. 1 through 9 are views for explaining processes included in a firstexemplary embodiment of a method of fabricating a light-emitting element1 (see FIG. 7) according to aspects of the present invention. Inparticular, FIGS. 2 and 3 show examples of photonic crystal patterns 106of FIG. 1. In addition, FIGS. 8 and 9 are views for explaining theoperation of the light-emitting element 1 according to the firstexemplary embodiment. The light-emitting element 1 according to thefirst exemplary embodiment may be of a lateral type or a flip-chip type.

Referring to FIG. 1, a buffer layer 108 is formed on a substrate 100.Specifically, the buffer layer 108 may be used as a seed layer forforming a first conductive layer 112 a, a light-emitting layer 114 a anda second conductive layer 116 a, which will be described herein below.In addition, the buffer layer 108 is used to prevent a lattice mismatchbetween the substrate 100 and a light-emitting structure 110 (see FIG.5), which will also be described herein below. Thus, the buffer layer108 improves the membranous properties of the light-emitting structure110 (see FIG. 5).

The buffer layer 108 may be made of any material that can make thebuffer layer 108 serve as a seed layer. For example, the buffer layer108 may be made of In_(x)Al_(y)Ga_((1-x-y))N (0≦x≦1, 0≦y≦1) orSi_(x)C_(y)N_((1-x-y)) (0≦x≦1, 0≦y≦1).

The buffer layer 108 may be grown on the substrate 100 by metal organicchemical vapor deposition (MOCVD), liquid phase epitaxy, hydride vaporphase epitaxy, molecular beam epitaxy, metal organic vapor phase epitaxy(MOVPE), or the like.

Next, the photonic crystal patterns 106 and a pad pattern 107 are formedon the buffer layer 108.

The photonic crystal patterns 106 allow light generated by thelight-emitting structure 110 (see FIG. 5) to easily come out of thelight-emitting element 1. That is, the photonic crystal patterns 106 canimprove the light extraction efficiency of the light-emitting element 1.

The photonic crystal patterns 106 may be a plurality of repetitive (orperiodic) patterns. The photonic crystal patterns 106 may have variousshapes. For example, the photonic crystal patterns 106 may be linepatterns (see FIG. 2) or may be mesh patterns (see FIG. 3). The photoniccrystal patterns 106 may be arranged at predetermined intervals denotedby “a”. When light generated by the light-emitting structure 110 has awavelength of λ, the interval “a” between every two adjacent ones of thephotonic crystal patterns 106 may be λ/4. Here, the interval “a” betweenevery two adjacent ones of the photonic crystal patterns 106 may becontrolled based on λ/4, that is, may be controlled to be substantiallyλ/4, with small variations tolerable.

The pad pattern 107 is used to receive power from a first electrode 140(see FIG. 7) which will be described later. When the pad pattern 107 istoo big, it is difficult to grow the first conductive layer 112 a (seeFIG. 4), the light-emitting layer 114 a (see FIG. 4), and the secondconductive layer 116 a (see FIG. 4). That is, when, for example, thefirst conductive layer 112 a is grown by liquid phase epitaxy, hydridevapor phase epitaxy, molecular beam epitaxy, or the like, it may fail togrow enough to completely cover an upper surface of the pad pattern 107.Therefore, the pad pattern 107 must be sized appropriately. For example,the pad pattern 107 may have a width of approximately 40 μm or less.

As shown in FIGS. 1 through 3, the photonic crystal patterns 106 may beformed at substantially the same level as the pad pattern 107. This ispossible because the photonic crystal patterns 106 and the pad pattern107 can be formed simultaneously, in some embodiments.

The photonic crystal patterns 106 may be physically connected to the padpattern 107. Therefore, when power is applied to the pad pattern 107 viathe first electrode 140, it is also delivered to the photonic crystalpatterns 106. Since power is applied to the photonic crystal patterns106 in this way, the flow of a bias current (e.g., electric current) canbe adjusted appropriately, which will be described in detail later withreference to FIG. 9.

The photonic crystal patterns 106 may be physically connected to the padpattern 107 as shown in FIGS. 2 and 3. However, the present invention isnot limited thereto. That is, the photonic crystal patterns 106 may bephysically connected to the pad pattern 107 in ways other than the waysshown in FIGS. 2 and 3. In addition, the photonic crystal patterns 106may be patterns other than those shown in FIGS. 2 and 3.

Each of the pad pattern 107 and the photonic crystal patterns 106 may bemade of a metal material such as a metal material having hightransparency or a metal material having high reflectivity. Examples ofthe metal material having high transparency may include indium tin oxide(ITO) and zinc oxide (ZnO), and examples of the metal material havinghigh reflectivity may include silver (Ag), aluminum (Al), rhodium (Rh),nickel-aurum (NiAu), palladium (Pd), and titanium-platinum (TiPt).

The substrate 100 may be made of any material from which the bufferlayer 108, the first conductive layer 112 a, the light-emitting layer114 a, and the second conductive layer 116 a can grow. For example, thesubstrate 100 may be an insulating substrate made of sapphire (Al₂O₃) orZnO or may be a conductive substrate made of silicon (Si), siliconcarbide (SiC), or gallium nitride (GaN).

Referring to FIG. 4, the first conductive layer 112 a, thelight-emitting layer 114 a, and the second conductive layer 116 a aresequentially stacked on the buffer layer 108 having the photonic crystalpatterns 106 and the pad pattern 107.

Specifically, each of the first conductive layer 112 a, thelight-emitting layer 114 a, and the second conductive layer 116 a mayinclude In_(x)Al_(y)Ga_((1-x-y))N (0≦x≦1, 0≦y≦1). For example, each ofthe first conductive layer 112 a, the light-emitting layer 114 a, andthe second conductive layer 116 a may be AlGaN or InGaN.

The first conductive layer 112 a, the light-emitting layer 114 a, andthe second conductive layer 116 a may be sequentially formed by MOCVD,liquid phase epitaxy, hydride vapor phase epitaxy, molecular beamepitaxy, MOVPE, or the like.

Specifically, the first conductive layer 112 a may have a firstconductivity type (e.g., an n type), and the second conductive layer 116a may have a second conductivity type (e.g., a p type). Conversely, thefirst conductive layer 112 a may be of the second conductivity type (thep type), and the second conductive layer 116 a may be of the firstconductivity type (the n type), depending on the embodiment of thelight-emitting element 1.

The light-emitting layer 114 a is a region where light is generated whencarriers (e.g., electrons) of the first conductive layer 112 a combinewith carriers (e.g., holes) of the second conductive layer 116 a.Although not specifically shown in the drawings, the light-emittinglayer 114 a may include a well layer and a barrier layer. Since the welllayer has a smaller band gap than the barrier layer, the carriers(electrons and holes) gather in the well layer and combine together. Thelight-emitting layer 114 a may have a single quantum well (SQW)structure or a multiple quantum well (MQW) structure, depending on thenumber of well layers included in the light-emitting layer 114 a. TheSQW structure includes only one well layer while the MQW structureincludes a plurality of well layers. In order to control light-emittingproperties, at least one of the well layer and the barrier layer may bedoped with at least one of boron (B), phosphorous (P), Si, magnesium(Mg), zinc (Zn), selenium (Se), and Al.

After the second conductive layer 116 a is formed, the substrate 100having the second conductive layer 116 a may be annealed to activate thesecond conductive layer 116 a. The substrate 100 may be annealed at atemperature of, e.g., approximately 400° C. Specifically, when thesecond conductive layer 116 a is In_(x)Al_(y)Ga_((1-x-y))N doped withMg, if the substrate 100 having the second conductive layer 116 a isannealed, hydrogen (H) combined with Mg is reduced. As a result, thesecond conductive layer 116 a shows p-type properties more clearly.

The first conductive layer 112 a may include a vertical conductive layer112 b which is disposed between every two adjacent ones of the photoniccrystal patterns 106 and a lateral conductive layer 112 c which isdisposed on each of the photonic crystal patterns 106. Here, the term“vertical” denotes a direction substantially perpendicular to a surfaceof the substrate 100, and the term “lateral” denotes a directionsubstantially parallel to the surface of the substrate 100.

The vertical conductive layer 112 b is grown from a portion of thesubstrate 100 exposed between every two adjacent ones of the photoniccrystal patterns 106. The horizontal conductive layer 112 c extends fromthe vertical conductive layer 112 b onto each of the photonic crystalpatterns 106. The lateral conductive layer 112 c corresponds to anover-growth region (or a lateral-growth region). The lateral conductivelayer 112 c has a relatively lower defect density than the verticalconductive layer 112 b. For example, the lateral conductive layer 112 cmay have a defect density of 10⁴cm⁻².

The photonic crystal patterns 106 may be used to improve lightextraction efficiency as described above or may be used to form thefirst conductive layer 112 a, the light-emitting layer 114 a, and thesecond conductive layer 116 a which have low defect densities. Since thelight-emitting layer 114 a and the second conductive layer 116 a aregrown from the first conductive layer 112 a having a low defect density,they also have low defect densities.

A second ohmic layer 132 is formed on the second conductive layer 116 a.The second ohmic layer 132 may include at least one of ITO, Zn, ZnO, Ag,Ti, Al, Au, Ni, indium oxide (In₂O₃), tin oxide (SnO₂), copper (Cu),tungsten (W), and Pt.

Referring to FIG. 5, the second conductive layer 116 a, thelight-emitting layer 114 a, and the first conductive layer 112 a arepatterned to form the light-emitting structure 110 which includes afirst conductive pattern 112, a light-emitting pattern 114, and a secondconductive pattern 116. Although not shown in the drawing, a lowerportion of the light-emitting structure 110 may be wider than an upperportion thereof. Thus, the light-emitting structure 110 may haveinclined sidewalls. In addition, the first conductive pattern 112 may bewider than the second conductive pattern 116 and the light-emittingpattern 114. Thus, the first conductive pattern 112 may have aprotruding portion in a lateral direction. The pad pattern 107 may bedisposed under the protruding portion of the first conductive pattern112.

Next, an insulating layer 120 is formed on the upper surface andsidewalls of the light-emitting structure 110. Then, a portion of theinsulating layer 120, which is disposed on the pad pattern 107, isetched to form a first opening op1 that penetrates the insulating layer120. In addition, a portion of the first conductive pattern 112, whichis disposed on the pad pattern 107, is etched to form a second openingop2 that penetrates the first conductive pattern 112.

Specifically, the portion of the insulating layer 120 may be wet-etchedto form the first opening op1, and the portion of the first conductivepattern 112 may be dry-etched to form the second opening op2. Here, thewet-etching process and the dry-etching process may be performed byusing the same mask (e.g., a photoresist pattern). Although the samemask is used to perform the wet-etching process and the dry-etchingprocess, since an undercut is formed in the wet-etching process, a widthW2 of the second opening op2 may be less than a width w1 of the firstopening op1.

Referring to FIG. 6, a first ohmic layer 131 may be formed to at leastpartially fill the first and second openings op1 and op2. Specifically,the first ohmic layer 131 may include at least one of ITO, Zn, ZnO, Ag,Ti, Al, Au, Ni, In₂O₃, SnO₂, Cu, W, and Pt. In order to activate thefirst ohmic layer 131, the substrate 100 having the first ohmic layer131 may be annealed at a temperature of, e.g., approximately 400° C.

As described above, the width W1 of the first opening op1 may be greaterthan the width w2 of the second opening op2. In this case, an area, inwhich the first ohmic layer 131 filling the first and second openingsop1 and op2 contacts the first conductive pattern 112, is increased(that is, is wider than when the width w1 of the first opening op1 isequal to the width w2 of the second opening op2). When the area, inwhich the first ohmic layer 131 filling the first and second openingsop1 and op2 contacts the first conductive pattern 112, is increased asdescribed above, power received from the first electrode 140 (see FIG.7) can better be delivered to the first conductive pattern 112.

Referring to FIG. 7, the insulating layer 120 is etched to expose thesecond ohmic layer 132. Then, a second electrode 150 is formed on theexposed second ohmic layer 132, and the first electrode 140 is formed onthe first ohmic layer 131.

When the light-emitting element 1 according to the first exemplaryembodiment is fabricated to be of the flip-chip type, the secondelectrode 150 may be made of a material having a high reflectivity. Forexample, the second electrode 150 may be made of Ag or Al to reflectlight generated by the light-emitting structure 110 so that the lightcan proceed toward the photonic crystal patterns 106. In order tomaximize the reflective properties of the second electrode 150, the areaof the second electrode 150 may be more than at least half the area ofan upper surface of the second conductive pattern 116. As the area ofthe second electrode 150 is increased, the amount of light reflected bythe second electrode 150 may increase.

When the light-emitting element 1 according to the first exemplaryembodiment is fabricated to be of the lateral type, the second electrode150 may be made of a material having a high transparency. For example,the second electrode 150 may be made of ITO so that light generated bythe light-emitting structure 110 can pass through the second electrode150 out of the light-emitting element 1. In order to maximizetransmissive properties of the second electrode 150, the area of thesecond electrode 150 may be minimized, for example, to an area (adiameter of 50 μm) that enables wire bonding.

The light-emitting element 1 according to the first exemplary embodimentof the present invention will now be described in more detail withreference to FIG. 7. The light-emitting element 1 according to the firstexemplary embodiment can be fabricated by using the method describedabove with reference to FIGS. 1 through 6.

Referring to FIG. 7, the light-emitting element 1 according to the firstexemplary embodiment includes the buffer layer 108, the photonic crystalpatterns 106, the pad pattern 107, the light-emitting structure 110, thefirst electrode 140, and the second electrode 150. The buffer layer 108is formed on the substrate 100. The photonic crystal patterns 106 andthe pad pattern 107 are formed on the buffer layer 108, made of metalmaterials, and are physically connected to each other. Thelight-emitting structure 110 includes the first conductive pattern 112of the first conductivity type, the light-emitting pattern 114, and thesecond conductive pattern 116 of the second conductivity type, which aresequentially stacked on the buffer layer 108. The buffer layer also hasthe photonic crystal patterns 106 and the pad pattern 107 disposedthereon. The first electrode 140 is electrically connected to the firstconductive pattern 112, and the second electrode 150 is electricallyconnected to the second conductive pattern 116.

In particular, the interval “a” between every two adjacent ones of thephotonic crystal patterns 106 may be λ/4 when visible light generated bythe light-emitting structure 110 has a wavelength of λ. Here, theinterval “a” between every two adjacent ones of the photonic crystalpatterns 106 may be controlled based on λ/4, that is, may be besubstantially λ/4, with small variations tolerable. Since the photoniccrystal patterns 106 affect the optical path, they may be arranged suchthat light can easily come out of the light-emitting element 1, therebyimproving the light extraction efficiency of the light-emitting element1.

Specifically, ultraviolet (UV) light and/or visible light may begenerated by the light-emitting structure 110. For example, when thelight-emitting structure 110 generates visible light having a wavelengthof 400 to 800 nm, the interval “a” between every two adjacent ones ofthe photonic crystal patterns 106 may be 100 to 400 nm, for example.

The operation of the light-emitting element 1 according to the firstexemplary embodiment will now be described.

Referring to FIG. 8, when the first conductive pattern 112 is of the ntype and when the second conductive pattern 116 is of the p type, afirst bias BIAS(−) is applied to the first conductive pattern 112 viathe first electrode 140, the first ohmic layer 131, the pad pattern 107and the photonic crystal patterns 106, and a second bias BIAS(+) isapplied to the second conductive pattern 116 via the second electrode150 and the second ohmic layer 132. Conversely, although not shown inFIG. 8, when the first conductive pattern 112 is of the p type and whenthe second conductive pattern 116 is of the n type, the second biasBIAS(+) is applied to the first conductive pattern 112 via the firstelectrode 140, the first ohmic layer 131, the pad pattern 107 and thephotonic crystal patterns 106, and the first bias BIAS(−) is applied tothe second conductive pattern 116 via the second electrode 150 and thesecond ohmic layer 132.

Thus, the light-emitting structure 110 is forward-biased in thisembodiment. The forward bias causes the light-emitting pattern 114 togenerate light L. Although not shown in the drawing, the generated lightL may be reflected by the second electrode 150 or may travel toward thephotonic crystal patterns 106. The light L can easily come out of thelight-emitting element 1 through the photonic crystal patterns 106.Specifically, since the photonic crystal patterns 106 induce paths ofthe light L, the light can easily come out of the light-emitting element1, which, in turn, improves the light extraction efficiency of thelight-emitting element 1.

Referring to FIG. 9, power applied to the first electrode 140 isdelivered to the photonic crystal patterns 106 and the pad pattern 107,which are physically connected to each other. Thus, the flow of bias(e.g., electric current) between the first electrode 140 and the secondelectrode 150 can be adjusted selectively and appropriately.

Specifically, the photonic crystal patterns 106 are widely distributedbetween the first conductive pattern 112 and the substrate 100, and thefirst bias BIAS(−) is also applied to the photonic crystal patterns 106.Therefore, as shown in FIG. 9, electric current I, which flows from thesecond electrode 150 to the first electrode 140, may evenly flow inalmost the entire region of the light-emitting structure 110. That is,light may be emitted from almost the entire region of the light-emittingpattern 114 of the light-emitting structure 110. Consequently, theamount of light emitted from the light-emitting element 1 can beincreased.

FIGS. 10 through 14 are views for explaining processes included in asecond exemplary embodiment of a method of fabricating a light-emittingelement 2 (see FIG. 14) according to aspects of the present invention.The light-emitting element 2 according to the second exemplaryembodiment of the present invention may be of the flip-chip type.

As shown in FIG. 1, a buffer layer 108 is formed on a substrate 100.Then, photonic crystal patterns 106 and a pad pattern 107 are formed onthe buffer layer 108. Then, as shown in FIG. 4, a first conductive layer112 a, a light-emitting layer 114 a, and a second conductive layer 116 aare sequentially formed on the buffer layer 108 having the photoniccrystal patterns 106 and the pad pattern 107 also formed thereon.

Referring to FIG. 10, the second conductive layer 116 a, thelight-emitting layer 114 a, and the first conductive layer 112 a arepatterned to form a light-emitting structure 110 which includes a firstconductive pattern 112, a light-emitting pattern 114, and a secondconductive pattern 116. As shown in the drawing, a lower portion of thelight-emitting structure 110 may be wider than an upper portion thereof.Thus, the light-emitting structure 110 may have inclined sidewalls. Inaddition, the first conductive pattern 112 may be wider than the secondconductive pattern 116 and the light-emitting pattern 114. Thus, thefirst conductive pattern 112 may have a protruding portion in a lateraldirection. The pad pattern 107 may be disposed under the protrudingportion of the first conductive pattern 112.

Referring to FIG. 11, an insulating layer 120 is formed on upper andside surfaces of the light-emitting structure 110. The insulating layer120 may include a silicon oxide film, a silicon nitride film, analuminum oxide (Al₂O₃) film, or an aluminum nitride (AlN) film. Theinsulating layer 120 may be formed by plasma enhanced chemical vapordeposition (PECVD), thermal oxidation, electron-beam evaporation, or thelike.

Next, a portion of the insulating layer 120 is etched to expose aportion of an upper surface of the second conductive pattern 116.

Referring to FIG. 12, a second ohmic layer 132 is formed on the exposedportion of the second conductive pattern 116. Then, a second electrode150 is formed on the insulating layer 120 and the second ohmic layer132. That is, the second electrode 150 is formed on the upper and sidesurfaces of the light-emitting structure 110 and an upper surface of theprotruding portion of the first conductive pattern 112. The secondelectrode 150 may have at least a portion shaped like a bowl, which isshown inverted, that covers the light-emitting structure 110.

Although not shown in the drawing, the second electrode 150 may beformed only on the upper surface of the light-emitting structure 110.

The second electrode 150 may be made of a material having highreflectivity. For example, the second electrode 150 may be made of Ag orAl to reflect light generated by the light-emitting structure 110 sothat the light can proceed toward the photonic crystal patterns 106.

Referring to FIG. 13, a portion of the insulating layer 120 and aportion of the second electrode 150 are etched to form a first openingop1. The first opening op1 penetrates the insulating layer 120 disposedon the pad pattern 107.

Then, the protruding portion of the first conductive pattern 112 ispartially etched to form a second opening op2. The second opening op2penetrates part of the first conductive pattern 112 disposed on the padpattern 107. Here, the second opening op2 may be narrower than the firstopening op1. As described above, the portion of the insulating layer 120and the portion of the second electrode 150 may be wet-etched to formthe first opening op1, and part of the protruding portion of the firstconductive pattern 112 may be dry-etched to form the second opening op2.Here, the wet-etching process and the dry-etching process may beperformed by using the same mask (e.g., a photoresist pattern).

Referring to FIG. 14, a first ohmic layer 131 is formed to at leastpartially fill the first and second openings op1 and op2. Then, a firstelectrode 140 is formed on the first ohmic layer 131 to complete thelight-emitting element 2 according to the second exemplary embodiment.

The light-emitting element 2 according to the second exemplaryembodiment of the present invention will now be described in moredetail.

The light-emitting element 2 according to the second exemplaryembodiment is different from the light-emitting element 1 according tothe first exemplary embodiment in that the second electrode 150 isformed not only on the upper surface of the light-emitting structure110, but also on the sidewalls of the light-emitting structure 110. Thatis, the second electrode 150 may have at least a portion shaped like abowl, which is shown inverted, that covers the light-emitting structure110.

Even when the second electrode 150 is formed on the side surfaces of thelight-emitting structure 110 (surrounds the light-emitting structure110), it does not electrically connect (i.e., does not causeshort-circuits between) the first conductive pattern 112 and the secondconductive pattern 116 since the insulating layer 120 is formed betweenthe second electrode 150 and the light-emitting structure 110. That is,the insulating layer 120 can prevent leakage current.

Since the light-emitting structure 110 has the inclined sidewalls, lightemitted from the light-emitting structure 110 is reflected by the secondelectrode 150 surrounding the light-emitting structure 110 and theneasily comes out of the light-emitting element 2 through the photoniccrystal patterns 106. That is, the light-emitting structure 110 whichhas the inclined sidewalls and the second electrode 150 that is inclinedalong the profile of the light-emitting structure 110 and has highreflectivity can improve light extraction efficiency.

FIGS. 15 through 19 are views for explaining processes included in athird exemplary embodiment of a method of fabricating a light-emittingelement 3 (see FIG. 19) according to aspects of the present invention.The light-emitting element 3 according to the third exemplary embodimentof the present invention may be of a vertical type.

Referring to FIG. 15, a sacrificial layer 102, a buffer layer 108,photonic crystal patterns 106, and a pad pattern 107 are sequentiallyformed on each of a plurality of substrates 100.

As will be described later, the sacrificial layer 102 is removed wheneach of the substrates 100 is removed by a laser lift-off (LLO) process.The sacrificial layer 102 may be, for example, a GaN layer.

The buffer layer 108 prevents the photonic crystal patterns 106 frombeing damaged during the LLO process and is used as a seed layer forsequentially forming (growing) a first conductive layer, alight-emitting layer and a second conductive layer. In addition, thebuffer layer 108 is used to prevent a lattice mismatch between each ofthe substrates 100 and the first conductive layer, the light-emittinglayer and the second conductive layer.

As described above, the photonic crystal patterns 106 improve lightextraction efficiency and induce lateral growth. Thus, the photoniccrystal patterns 106 are used to form the first conductive layer, thelight-emitting layer, and the second conductive layer having low defectdensities. The photonic crystal patterns 106 may include a plurality ofrepetitive (or periodic) patterns of photonic crystals. The photoniccrystal patterns 106 may be arranged at predetermined intervals “a”.When light generated by a light-emitting structure 110 (see FIG. 16) hasa wavelength of λ, the interval “a” between every two adjacent ones ofthe photonic crystal patterns 106 may be λ/4. Here, the interval “a”between every two adjacent ones of the photonic crystal patterns 106 maybe controlled based on λ/4, that is, may be substantially λ/4, withsmall variations tolerable.

As described above, the photonic crystal patterns 106 and the padpattern 107 may be made of metal materials and physically connected toeach other. In addition, the photonic crystal patterns 106 may be formedat substantially the same level as the pad pattern 107.

Referring to FIG. 16, the first conductive layer, the light-emittinglayer, and the second conductive layer are sequentially grown on each ofthe substrates 100, which has the photonic crystal patterns 106 and thepad pattern 107 formed thereon.

Then, the second conductive layer, the light-emitting layer, and thefirst conductive layer are patterned to form the light-emittingstructure 110, which includes a first conductive pattern 112, alight-emitting pattern 114, and a second conductive pattern 116. A lowerportion of the light-emitting structure 110 may be wider than an upperportion thereof. Thus, the light-emitting structure 110 may haveinclined sidewalls.

Next, an insulating layer 120 is formed on upper and side surfaces ofthe light-emitting structure 110.

Then, a portion of the insulating layer 120 is etched to expose aportion of an upper surface of the second conductive pattern 116.

A second ohmic layer 132 is formed on the exposed portion of the secondconductive pattern 116.

A second electrode 150 is formed on the upper and side surfaces of thelight-emitting structure 110. That is, the second electrode 150 isconformally formed on the second ohmic layer 132 and the insulatinglayer 120. Therefore, the second electrode 150 may have at least aportion shaped like a bowl, which is shown inverted, that covers thelight-emitting structure 110.

Referring to FIG. 17, each of the substrates 100 is bonded to aconductive substrate 200. Here, the second electrode 150 is disposedbetween the conductive substrate 200 and each of the substrates 100.

Specifically, the conductive substrate 200 may be made of one of Si,strained Si, Si—Al, silicon alloy, silicon-on-insulator (SOI), SiC,silicon germanium (SiGe), silicon germanium carbide (SiGeC), germanium(Ge), Ge alloy, gallium arsenide (GaAs), indium arsenide (InAs), III-Vsemiconductor, and II-VI semiconductor, as examples.

Preferably, in this embodiment, the substrates 100 or the conductivesubstrate 200, or both, may be substantially flat because it is hard tosufficiently bond the substrates 100 and 200 together when each of thesubstrates 100 or the conductive substrate 200 is other than flat, e.g.,bent. As will be described later, since an intermediate material layer210 is disposed between each of the substrates 100 and the conductivesubstrate 200, the intermediate material layer 210 (in particular, whenthe intermediate material layer 210 has a sufficient thickness) cancompensate for the slight bending of each of the substrates 100 or theconductive substrate 200.

For example, the conductive substrate 200 may be adhesively bonded tothe substrates 100. Preferably, the conductive substrate 200 and thesubstrates 100 are washed before bonding. It is desirable for bondingsurfaces of the substrates 100 and 200 to be clean because variousimpurities (such as particles and dust) on the bonding surfaces of thesubstrates 200 and 100 can become sources of contamination. That is,when the conductive substrate 200 is bonded to the substrates 100, ifthe above impurities exist between the substrates 200 and 100, bondingenergy can be reduced. As a result, the substrates 200 and 100 can beeasily separated from each other.

Next, the intermediate material layer 210 is formed on the bondingsurface of the conductive substrate 200 or the bonding surface of eachof the substrates 100. In FIG. 17, the intermediate material layer 210is formed on the bonding surface of the conductive substrate 200.Although not shown in the drawing, the intermediate material layer 210may be conformally formed along the profile of the second electrode 150of each of the substrates 100. Alternatively, after the intermediatematerial layer 210 is formed on the upper surface of the secondelectrode 150 of the light-emitting structure 110, each of thesubstrates 100 may be bonded to the conductive substrate 200.

The intermediate material layer 210 may be a conductive material, e.g.,a metal layer. When the intermediate material layer 210 is a metallayer, the metal layer may include at least one of Au, Ag, Pt, Ni, Cu,Sn, Al, Pb, Cr, and Ti. That is, the metal layer may be a monolayer madeof one of Au, Ag, Pt, Ni, Cu, Sn, Al, Pb, Cr and Ti, a stack of thesame, or a combination of the same. For example, the metal layer may bean Au layer (a monolayer), an Au—Sn layer (a double layer), or amulti-layer having Au and Sn alternately stacked several times. Theintermediate material layer 210 may be made of a material having lowerreflectivity than that of the second electrode 150.

Although not shown in the drawing, a barrier layer may be formed betweenthe second electrode 150 and the intermediate material layer 210. Thebarrier layer prevents the second electrode 150, which reflects light,from being damaged. The barrier layer may be a monolayer made of one ofPt, Ni, Cu, Al, Cr, Ti and W, a stack of the same, or a combination ofthe same. For example, the barrier layer may be a multi-layer having TiWand Pt alternately stacked several times.

Next, as shown in FIG. 17, the second electrode 150 formed on each ofthe substrates 100 is made to face the bonding surface of the conductivesubstrate 200, with the intermediate material layer 210 disposed betweenthe two.

Then, the substrates 200 and 100 are heat-treated and thus bondedtogether. Alternatively, while the substrates 200 and 100 areheat-treated, they may be pressed against each other and thus bondedtogether.

When the intermediate material layer 210 is an Au layer, the substrates200 and 100 may be pressed against each other at a temperature ofapproximately 200 to 450° C. The temperature used can be determined byone of ordinary skill in the art to which the present inventionpertains, without undue experimentation.

In order to increase throughput, the substrates 100 may be bonded to theone conductive substrate 200 as shown in FIG. 18. Specifically, theconductive substrate 200 is larger than each of the substrates 100,i.e., has a larger surface area sufficient for mounting a plurality ofsubstrates 100. That is, the conductive substrate 200 completely hideseach of the substrates 100 when put on top of each of the substrates100. When the substrates 100 and 200 are circular, a diameter of theconductive substrate 200 may be greater than that of each of thesubstrates 100. For example, the diameter of the conductive substrate200 may be about 6 inches (approximately 150 mm) or greater, and that ofeach of the substrates 100 may be less than about 6 inches. When thesubstrates 100 and 200 are square shaped, a diagonal length of theconductive substrate 200 may be greater than that of each of thesubstrates 100. Here, the second electrode 150 formed on each of thesubstrates 100 is made to face the bonding surface of the conductivesubstrate 200.

When throughput is not a concern, each of the substrates 100 may besubstantially the same size as the conductive substrate 200. That is,one of the substrates 100 may be bonded to the conductive substrate 200.

Referring to FIG. 19, each of the substrates 100 is removed by removingthe sacrificial layer 102. Specifically, each of the substrates 100 maybe removed by an LLO process or a chemical lift-off (CLO) process.

In the case of the LLO process, a laser beam is radiated from the sideof each of the substrates 100. When the sacrificial layer 102 is removedby using a laser beam, each portion of each of the substrates 100 issequentially removed, starting with a portion to which the laser beam isradiated.

In order to prevent the light-emitting element 3 from being damagedduring the LLO process, a thickness of each of the substrates 100 may bereduced before the LLO process is performed. As described above, eachportion of each of the substrates 100 may be sequentially removedstarting with a portion to which a laser beam is radiated. Thus, thelight-emitting structure 110 may be broken or damaged by physical forceapplied when each of the substrates 100 is removed. However, if thethickness of each of the substrates 100 is reduced in advance by, e.g.,chemical mechanical polishing (CMP), the light-emitting structure 110can be prevented from being damaged since the physical force appliedwhen each of the substrates 100 is removed is reduced.

The buffer layer 108 prevents a first electrode 140 from being damagedduring the LLO process.

Referring to FIG. 19, a portion of the buffer layer 108, which isexposed after each of the substrates 100 is removed, is etched to exposethe pad pattern 107. Here, the portion of the buffer layer 108 is etchedto expose at least part of the pad pattern 107.

Next, a first ohmic layer 131 is formed on the exposed portion of thepad pattern 107.

Then, the first electrode 140 is formed on the first ohmic layer 131 tocomplete the light-emitting element 3 according to the third exemplaryembodiment.

The light-emitting element 3 according to the third exemplary embodimentincludes the second electrode 150, the light-emitting structure 110, thephotonic crystal patterns 106, and the pad pattern 107. The secondelectrode 150 is formed on the conductive substrate 200 and isbowl-shaped. The light-emitting structure 110 includes the secondconductive pattern 116, the light-emitting pattern 114, and the firstconductive pattern 112 which are sequentially formed on the secondelectrode 150. The photonic crystal patterns 106 and the pad pattern 107are formed on the first conductive pattern 112. As described above, thephotonic crystal patterns 106 and the pad pattern 107 may be made ofmetal materials and physically connected to each other. In addition, thephotonic crystal patterns 106 may be formed at substantially the samelevel as the pad pattern 107.

The buffer layer 108 is formed on the first conductive pattern 112having the photonic crystal patterns 106 and the pad pattern 107 andexposes at least part of the pad pattern 107. The first ohmic layer 131is formed on the exposed portion of the pad pattern 107, and the firstelectrode 140 is formed on the first ohmic layer 131. That is, the firstelectrode 140 is electrically connected to the first conductive pattern112 by the first ohmic layer 131.

The buffer layer 108 may be more resistant than the first conductivepattern 112 because the first conductive pattern 112 may be doped withdopants of the first conductivity type while the buffer layer 108 maynot be. Therefore, the first electrode 140 may be electrically connectedto the pad pattern 107 by the first ohmic layer 131 such that powerapplied to the first electrode 140 can be delivered to the pad pattern107 and the first conductive pattern 112 without a significant drop inthe power level.

FIG. 20 is a view for explaining a fourth exemplary embodiment of alight-emitting element 4 according to aspects of the present invention.

Referring to FIG. 20, the light-emitting element 4 according to thefourth exemplary embodiment is different from the light-emitting element3 according to the third exemplary embodiment in that a protrusion 151is formed on a bowl-shaped second electrode 150 and that the protrusion151 creates a groove 118 in a light-emitting structure 110 formed in thesecond electrode 150.

The light-emitting structure 110 may be divided into a first side (e.g.,the left side of the drawing) and a second side (e.g., the right side ofthe drawing) by the protrusion 151 or the groove 118. A pad pattern 107may be formed on the second side of the light-emitting structure 110,and photonic crystal patterns 106 may be formed on the first side of thelight-emitting structure 110.

Even in this configuration, the pad pattern 107 is physically connectedto the photonic crystal patterns 106, and power applied to the firstelectrode 140 is delivered to the photonic crystal patterns 106 via thepad pattern 107. The flow of electric current between the firstelectrode 140 and the second electrode 150 can be adjustedappropriately, thereby improving light emission efficiency.

Hereinafter, a light-emitting device fabricated by using one of thelight-emitting elements 1 through 4 will be described in detail. Forsimplicity, a light-emitting device using the light-emitting element 1according to the first exemplary embodiment is shown in the drawings.However, the scope of the present invention is not limited thereto. Itwill be apparent to those of ordinary skill in the art to which thepresent invention pertains, having the benefit of this disclosure, thatone can implement a light-emitting device similar to the light-emittingdevice using the light-emitting element 1 by using any one of thelight-emitting elements 2 through 4.

FIG. 21A is a view for explaining a first exemplary embodiment of alight-emitting device 11 according to aspects of the present invention.

Referring to FIG. 21A, the light-emitting device 11 according to thefirst exemplary embodiment includes a circuit board 300 and thelight-emitting element 1 according to the first exemplary embodiment,which is disposed on the circuit board 300. The light-emitting element 1may be connected to the circuit board 300 by a submount 250.

The circuit board 300 includes a first conductive region 310 and asecond conductive region 320 which are electrically insulated from eachother. The first conductive region 310 and the second conductive region320 are disposed on a surface of the circuit board 300.

The submount 250 includes a third conductive region 260 and a fourthconductive region 270 that are electrically insulated from each other.The third conductive region 260 and the fourth conductive region 270 aredisposed on a surface of the submount 250.

The second electrode 150 of the light-emitting element 1 may beconnected to the third conductive region 260 of the submount 250 by oneof conductive solders 280, and the third conductive region 260 may beconnected to the first conductive region 310 by a wire 330. The firstelectrode 140 of the light-emitting element 1 may be connected to thefourth conductive region 270 of the submount 250 by the other one of theconductive solders 280, and the fourth conductive region 270 may beconnected to the second conductive region 320 by a wire 332. However, itwill be apparent to those of ordinary skill in the art to which thepresent invention pertains, having the benefit of this disclosure, thatone can connect the above components in different ways other than theway shown in FIG. 21A.

FIG. 21B is a view for explaining a second exemplary embodiment of alight-emitting device 12 according to aspects of the present invention.Referring to FIG. 21B, the light-emitting device 12 according to thesecond exemplary embodiment is different from the light-emitting device11 according to the first exemplary embodiment in that a circuitsubstrate 300 includes first and second through vias 316 and 326.

Specifically, a first conductive region 310 and a second conductiveregion 320, which are electrically insulated from each other, are formedon a surface of the circuit board 300, and a fifth conductive region 312and a sixth conductive region 322, which are electrically insulated fromeach other, are formed on the other surface of the circuit board 300.The first conductive region 310 is connected to the fifth conductiveregion 312 by the first through vias 316, and the second conductiveregion 320 is connected to the sixth conductive region 322 by the secondthrough vias 326.

Although not shown in the drawing, the second electrode 150 of thelight-emitting element 1 according to the first exemplary embodiment isconnected to the first conductive region 310 of the circuit board 300 byone of conductive solders 280. The first electrode 140 of thelight-emitting element 1 is connected to the second conductive region320 of the circuit board 300 by the other one of the conductive solders280. The first conductive region 310 may be connected to the fifthconductive region 312 by the first through vias 316, and the secondconductive region 320 may be connected to the sixth conductive region322 by the second through vias 326.

FIG. 21C is a view for explaining a third exemplary embodiment of alight-emitting device 13 according to aspects of the present invention.Referring to FIG. 21C, the light-emitting device 13 according to thethird exemplary embodiment is different from the light-emitting device11 according to the first exemplary embodiment in that a submount 251 isa conductive substrate.

Therefore, in order to prevent short circuits between a third conductiveregion 260 and the fourth conductive region 270, an insulating film 271is interposed between a fourth conductive region 270 and the submount251.

Since the submount 251 is a conductive substrate, a first conductiveregion 310 may be electrically connected to the third conductive region260 by the conductive substrate without requiring a wire. On the otherhand, a second conductive region 320 is connected to the fourthconductive region 270 by a wire 332.

FIG. 22 is a view for explaining a fourth exemplary embodiment of alight-emitting device 14 according to aspects of the present invention.Referring to FIG. 22, the light-emitting device 14 according to thefourth exemplary embodiment is different from the light-emitting device11 according to the first exemplary embodiment in that it includes aphosphor layer 340 surrounding the light-emitting element 1 according tothe first exemplary embodiment and second transparent resin 350 whichsurrounds the phosphor layer 340.

The phosphor layer 340 may be a mixture of first transparent resin 342and phosphors 344. The phosphors 344 dispersed within the phosphor layer340 absorb light emitted from the light-emitting element 1 and convertthe wavelength of the light. Thus, as the phosphors 344 are dispersedmore evenly, the light-emitting properties of the light-emitting device14 can be improved. When the phosphors 344 are dispersed more evenly,they can better convert the wavelength of light and produce a bettercolor mixture. As shown in the drawing, the phosphor layer 340 may beformed higher than a wire 332 in order to protect the wire 332, sincethe wire is surrounded by the phosphor layer 340.

For example, the light-emitting device 14 may include the phosphor layer340 formed to produce the color white. When the light-emitting element 1emits light having a blue wavelength, the phosphors 344 may includeyellow phosphors. In order to increase a color-rending index (CRI), thephosphors 344 may also include red phosphors. Alternatively, when thelight-emitting element 1 emits light having a UV wavelength, thephosphors 344 may include all of red, green, and blue phosphors.

The first transparent resin 342 may be any material that can dispersethe phosphors 344 in a stable manner. For example, the first transparentresin 342 may be epoxy resin, silicon resin, hard silicon resin,denatured silicon resin, urethane resin, oxetane resin, acrylic resin,polycarbonate resin, or polyimide resin.

The phosphors 344 may be any material that can absorb light from thelight-emitting structure 110 and convert the wavelength of the absorbedlight. For example, the phosphors 344 may be at least one ofnitride-based or oxynitride-based phosphors activated mainly by alanthanoid element such as europium (Eu) or cerium (Ce); alkaline earthhalogen apatite phosphors activated mainly by a lanthanoid element suchas Eu or a transition metal element such as manganese (Mn); alkalineearth metal halogen borate phosphors; alkaline earth metal aluminatephosphors; alkaline earth silicate phosphors; alkaline earth sulfidephosphors; alkaline earth thiogallate phosphors; alkaline earth siliconnitride phosphors; germanate phosphors; rare earth aluminate phosphorsactivated mainly by a lanthanoid element such as Ce; rare earth silicatephosphors; and organic or organic complex phosphors activated mainly bya lanthanoid element such as Eu. Specifically, phosphors listed belowmay be used. However, the phosphors 344 are not limited to the followingphosphors.

Examples of nitride-based phosphors activated mainly by a lanthanoidelement such as Eu or Ce include M₂Si₅N₈:Eu (M is at least one of Sr,Ca, Ba, Mg and Zn), MSi₇N₁₀:Eu, M_(1.8)Si₅O_(0.2)N₈:Eu, andM_(0.9)Si₇O_(0.1)N₁₀:Eu (M is at least one of Sr, Ca, Ba, Mg and Zn).

Examples of oxynitride-based phosphors activated mainly by a lanthanoidelement such as Eu or Ce include MSi₂O₂N₂:Eu (M is at least one of Sr,Ca, Ba, Mg and Zn).

Examples of alkaline earth halogen apatite phosphors activated mainly bya lanthanoid element such as Eu or a transition metal element such as Mninclude M₅(PO₄)₃X:R (M is at least one of Sr, Ca, Ba, Mg and Zn, X is atleast one of F, Cl, Br and I, and R is at least one of Eu and Mn).

Examples of alkaline earth metal halogen borate phosphors includeM₂B₅O₉X:R (M is at least one of Sr, Ca, Ba, Mg and Zn, X is at least oneof F, Cl, Br and I, and R is at least one of Eu and Mn).

Examples of alkaline earth metal aluminate phosphors include SrAl₂O₄:R,Sr₄Al₁₄O₂₅:R, CaAl₂O₄:R, BaMg₂Al₁₆O₂₇:R, BaMg₂Al₁₆O₁₂:R, andBaMgAl₁₀O₁₇:R (R is at least one of Eu and Mn).

Examples of alkaline earth sulfide phosphors include La₂O₂S:Eu,Y₂O₂S:Eu, and Gd₂O₂S:Eu.

Examples of rare earth aluminate phosphors activated mainly by alanthanoid element such as Ce include YAG phosphors represented bycompositional formulas such as Y₃Al₅O₁₂:Ce, (Y_(0.8)Gd_(0.2))₃Al₅O₁₂:Ce,Y₃(Al_(0.8)Ga_(0.2))₅O₁₂:Ce, and (Y, Gd)₃(Al, G)₅O₁₂. Other examplesinclude phosphors such as Tb₃Al₅O₁₂:Ce and Lu₃Al₅O₁₂:Ce in which part orall of Y has been replaced by Th, Lu, or the like.

Rare earth silicate phosphors contain silicate, and major examples ofthe rare earth silicate phosphors include (SrBa)₂SiO₄:Eu.

Examples of other phosphors include ZnS:Eu, Zn₂GeO₄:Mn, and MGa₂S₄:Eu (Mis at least one of Sr, Ca, Ba, Mg and Zn, and X is at least one of F,Cl, Br, and I).

The above phosphors may also include at least one of Th, Cu, Ag, Au, Cr,Nd, Dy, Co, Ni and Ti, instead of or in addition to Eu. Furthermore,other phosphors that offer similar performance and effects to thephosphors listed above can also be used.

The second transparent resin 350 is lens-shaped and diffuses lightemitted from the light-emitting element 1. The curvature and flatness ofthe second transparent resin 350 may be adjusted to control the lightdiffusion/extraction properties of the second transparent resin 350. Thesecond transparent resin 350 surrounds the phosphor layer 340 to protectthe phosphor layer 340. That is, the second transparent resin 350surrounds the phosphor layer 340 because the properties of the phosphorlayer 340 may deteriorate when contacting, for example, moisture.

The second transprent resin 350 may be any material through which lightcan pass. For example, the second transparent resin 350 may be epoxyresin, silicon resin, hard silicon resin, denatured silicon resin,urethane resin, oxetane resin, acrylic resin, polycarbonate resin, orpolyimide resin.

FIG. 23 is a view for explaining a fifth exemplary embodiment of alight-emitting device 15 according to aspects of the present invention.Referring to FIG. 23, phosphors 344 are formed along the profile of thelight-emitting element 1 according to the first exemplary embodiment andthe profile of a circuit board 300. Here, the phosphors 344 may becoated on the light-emitting element 1 and the circuit board 300 withoutrequiring first transparent resin (indicated by reference numeral 342 inFIG. 22).

If the phosphors 344 are coated on the light-emitting element 1 and thecircuit board 300 without requiring the first transparent resin, thelight-emitting element 1 is surrounded by a monolayer 350 of transparentresin.

FIG. 24 is a view for explaining a sixth exemplary embodiment of alight-emitting device 16 according to aspects of the present invention.Referring to FIG. 16, the light-emitting device 16 according to thesixth exemplary embodiment is different from the light-emitting device13 according to the third exemplary embodiment in that it includes firsttransparent resin 342, which surrounds the light-emitting element 1according to the first exemplary embodiment, phosphors 344 which areformed on the first transparent resin 342, and second transparent resin350 which is formed on the phosphors 344. That is, since the firsttransparent resin 342 and the phosphors 344 are coated separatelywithout being mixed with each other, the phosphors 344 may be formedthinly and conformally along a surface of the first transparent resin342.

FIG. 25 is a view for explaining a seventh exemplary embodiment of alight-emitting device 17 according to aspects of the present invention.The light-emitting device 17 shown in FIG. 25 is a top view-typelight-emitting package. However, the present invention is not limitedthereto.

Referring to FIG. 25, a submount 250 on which the light-emitting element1 according to the first exemplary embodiment is mounted is disposed ona package body 210. Specifically, a opening 212 is formed in the packagebody 210, and the submount 250 having the light-emitting element 1mounted thereon is disposed in the opening 212. The opening 212 may haveinclined sidewalls. Thus, light emitted from the light-emitting element1 may be reflected by the sidewalls and then proceed forward. The sizeof the opening 212 may be determined in consideration of the degree towhich light generated by the light-emitting element 1 is reflected bythe sidewalls of the opening 212, the angle at which the light isreflected by the sidewalls of the opening 212, the type of transparentresin that fills the opening 212, the type of phosphors, and the like.The submount 250 is preferably placed in the center of the opening 212since chromatic non-uniformity can be easily prevented when thelight-emitting element 1 is equidistant from the sidewalls of theopening 212.

The package body 210 may be made of an exceptionally lightfast organicmaterial, such as silicon resin, epoxy resin, acrylic resin, urea resin,fluorine resin or imide resin, or may be made of an exceptionallylightfast inorganic material such as glass or silica gel. In addition,thermosetting resin may be used in order to prevent the package body 210from melting due to heat while the light-emitting device 17 is beingfabricated. Various fillers, such as aluminum nitride, aluminum oxide,and compounds of the same, may be added to resin in order to relievethermal stress of the resin. The package body 210 may also be made of amaterial other than resin. For example, part (e.g., the sidewalls) orall of the package body 210 may be made of a metal material or a ceramicmaterial. When all of the package body 210 is made of a metal material,heat generated by the light-emitting element 1 can be easily dissipatedout of the package body 210.

Leads 214 a and 214 b are formed in the package body 210 and areelectrically connected to the light-emitting element 1. Thelight-emitting element 1 may be electrically connected to the submount250, and the submount 250 may be connected to the leads 214 a and 214 bby vias. The leads 214 a and 214 b may be made of a highly thermallyconductive material since heat generated by the light-emitting element 1can be dissipated directly out of the package body 210 through the leads214 and 214 b when the leads 214 a and 214 b are made of a highlythermally conductive material.

Although not shown in the drawing, at least part of the opening 212 maybe filled with a transparent resin layer. In addition, phosphors may beformed on the transparent resin layer. Alternatively, the transparentresin layer may be mixed with the phosphors.

For example, phosphors may be used as follows in order to produce thecolor white. When the light-emitting element 1 emits light having a bluewavelength, phosphors may include yellow phosphors. In order to increasethe CRI, the phosphors may also include red phosphors. Alternatively,when the light-emitting element 1 emits light having a UV wavelength,the phosphors may include all of red, green, and blue phosphors.

FIGS. 26 through 28 are views for explaining an eighth exemplaryembodiment of a light-emitting device 18 according to aspects of thepresent invention. Specifically, FIGS. 26 through 28 are views forexplaining an array of the light-emitting elements 1 according to thefirst exemplary embodiment, which are disposed on a circuit board 300.In particular, FIGS. 27 and 28 show phosphor layers 340 and secondtransparent resin 350 formed on the array of the light-emitting elements1.

Referring to FIG. 26, a first conductive region 310 and a secondconductive region 320 are formed on the circuit board 300 and extend ina direction to be parallel to each other. The light-emitting elements 1are arranged in a line in the direction in which the first conductiveregion 310 and the second conductive region 320 extend. As describedabove, the second electrode 150 of each of the light-emitting elements 1may be connected to the first conductive region 310 by a submount 250and a wire 330, and the first electrode 140 of each of thelight-emitting elements 1 may be connected to the second conductiveregion 320 by the submount 250 and a wire 332.

When appropriate biases are applied to the first conductive region 310and the second conductive region 320, the light-emitting structure 110(see FIG. 1) of each of the light-emitting elements 1 may beforward-biased. Thus, each of the light-emitting elements 1 may emitlight.

Referring to FIG. 27, the phosphor layers 340 and the second transparentresin 350 may be formed in a linear manner. For example, when thelight-emitting elements 1 are arranged in the direction in which thefirst conductive region 310 extends, the phosphor layers 340 and thesecond transparent resin 350 may also extend in the direction in whichthe first conductive region 310 extends. In addition, the phosphors 340and the second transparent resin 350 may completely surround the firstconductive region 310 and the second conductive region 320.

Referring to FIG. 28, the phosphor layers 340 and the second transparentresin 350 may be formed in a dotted manner. In this case, each of thephosphor layers 340 and each of the second transparent resin 350 maysurround a corresponding one of the elements 1.

FIG. 29 is a view for explaining a ninth exemplary embodiment of alight-emitting device according to aspects of the present invention.Specifically, the light-emitting device shown in FIG. 29 is an endproduct. The light-emitting device of FIG. 29 can be applied to variousapparatuses, such as lighting apparatuses, display apparatuses, andmobile apparatuses (mobile phones, MP3 players, navigations, etc.). Thelight-emitting device shown in FIG. 29 is an edge-type backlight unit(BLU) used in a liquid crystal display (LCD). Since LCDs are notself-luminous, they use a BLU as their light source. Generally, a BLU isdisposed behind a liquid crystal panel and provides light to the liquidcrystal panel.

Referring to FIG. 29, the BLU includes the light-emitting element 1according to the first exemplary embodiment, a light guide plate 410, areflective plate 412, a diffusion sheet 414, and a pair of prism sheets416. The light-emitting element 1 provides light and may be of aside-view type.

The light guide plate 410 guides light toward a liquid crystal panel450. The light guide plate 410 is a panel made of a transparent plasticmaterial such as acryl and guides light emitted from the light-emittingdevice toward the liquid crystal panel 450, which is disposed above thelight guide plate 410. Thus, various patterns 412 a are printed at theback of the light guide plate 410 to guide light, which is input to thelight guide plate 410, toward the liquid crystal panel 450.

The reflective plate 412 is disposed on a lower surface of the lightguide plate 410 and thus reflects upward light that is emitted downwardfrom the light guide plate 410. That is, the reflective plate 412reflects light, which is not reflected by the various patterns 412 aprinted at the back of the light guide plate 410, toward an outputsurface of the light guide plate 410. In so doing, the reflective plate412 reduces light loss and improves the uniformity of light which isoutput from the output surface of the light guide plate 410.

The diffusion sheet 414 diffuses light output from the light guide plate410, thereby preventing the light from being concentrated in a specificarea.

Each of the prism sheets 416 has a predetermined array of triangularprisms on an upper surface thereof. The prism sheets 416 typicallyconsist of two sheets, and an array of triangular prisms formed on oneof the two prism sheets 416 crosses an array of triangular prisms formedon the other one of the two prism sheets 416 at a predetermined angle sothat light diffused by the diffusion sheet 414 can proceed in adirection perpendicular to the liquid crystal panel 450.

FIGS. 30 through 33 are views for explaining tenth through thirteenthexemplary embodiments of light-emitting devices according to aspects ofthe present invention. FIGS. 30 through 33 show exemplary end productsto which the light-emitting devices according to the tenth throughthirteenth exemplary embodiments can be applied. Specifically, FIG. 30shows a projector, FIG. 31 shows a headlight of a vehicle, FIG. 32 showsa streetlight, and FIG. 33 shows a lamp. The light-emitting element 1used in FIGS. 30 through 33 may be of a top-view type.

Referring to FIG. 30, light emitted from a light source 410 passesthrough a condensing lens 420, a color filter 430, and a sharpening lens440. Then, the light is reflected by a digital micro-mirror device 450and passes through a projection lens 480 to reach a screen 490. Alight-emitting element according to the present invention is included inthe light source 410 of FIG. 30.

In FIG. 31, an embodiment of a headlight of a vehicle is shown, whereinthe light-emitting element 1 can be used in a main beam light, high beamlight, and/or directional light.

In FIG. 32, an embodiment of a street light is shown, wherein thelight-emitting element 1 can be used. The light emitting element 1 couldbe used in other forms of roadway lights or signals too, such as trafficsignals, crosswalk signals, and so on.

In FIG. 33, an embodiment of a lamp is shown, which could be used on awide variety of circumstances.

While embodiment in accordance with the present invention have beenparticularly shown and described, it will be understood by those ofordinary skill in the art that various changes in form and detail may bemade therein without departing from the spirit and scope of the presentinvention as defined by the following claims. The exemplary embodimentsshould be considered in a descriptive sense only and not for purposes oflimitation.

1. A method of fabricating a light-emitting element, the method comprising: forming a buffer layer on a substrate; forming photonic crystal patterns and a pad pattern on the buffer layer, each of the pad pattern and the photonic crystal patterns being made of a metal material, including physically connecting the pad patterns to the photonic crystal patterns; forming a light-emitting structure, including sequentially stacking a first conductive pattern of a first conductivity type, a light-emitting pattern, and a second conductive pattern of a second conductivity type on the buffer layer; and forming a first electrode and electrically connecting the first electrode to the first conductive pattern and forming a second electrode and electrically connecting the second electrode to the second conductive pattern.
 2. The method of claim 1, including forming the photonic crystal patterns at substantially the same level as the pad pattern.
 3. The method of claim 1, wherein the photonic crystal patterns are a plurality of repetitively formed patterns, and an interval between every two adjacent ones of the repetitive patterns is λ/4 and light generated by the light-emitting structure has a wavelength of λ.
 4. The method of claim 1, wherein the photonic crystal patterns are line patterns or mesh patterns.
 5. The method of claim 1, wherein the second electrode is formed on an upper surface and sidewalls of the light-emitting structure.
 6. The method of claim 1, wherein the forming of the light-emitting structure comprises: sequentially forming a first conductive layer of the first conductivity type, a light-emitting layer, and a second conductive layer of the second conductivity type on the buffer layer; and patterning the second conductive layer, the light-emitting layer, and the first conductive layer to complete the light-emitting structure comprising the second conductive pattern, the light-emitting pattern, and the first conductive pattern, wherein the first conductive pattern is wider than the second conductive pattern and the light-emitting pattern and the first conductive pattern has a protruding portion extending in a lateral direction, and the pad pattern is disposed under the protruding portion of the first conductive pattern.
 7. The method of claim 6, wherein the forming of the first electrode comprises: patterning part of the protruding portion of the first conductive pattern to expose the pad pattern; forming an ohmic layer on the exposed pad pattern; and forming the first electrode on the ohmic layer.
 8. The method of claim 6, further comprising: forming an insulating layer on the upper surface and sidewalls of the light-emitting structure after forming the light-emitting structure, wherein the forming of the first electrode comprises: etching a portion of the insulating layer to form a first opening that penetrates the insulating layer; etching a portion of the first conductive pattern to form a second opening that penetrates the first conductive pattern, the second opening being narrower than the first opening; forming an ohmic layer which at least partially fills the first opening and the second opening; and forming the first electrode on the ohmic layer.
 9. The method of claim 1, wherein the forming of the first electrode and the second electrode comprises: forming the second electrode on the light-emitting structure after forming the light-emitting structure; bonding the substrate to a conductive substrate such that the second electrode is disposed between the substrate and the conductive substrate; removing the substrate; and forming the first electrode on the buffer layer.
 10. The method of claim 9, wherein the forming of the first electrode on the buffer layer comprises: etching a portion of the buffer layer to expose at least part of the pad pattern; forming an ohmic layer on the exposed portion of the pad pattern; and forming the first electrode on the ohmic layer.
 11. The method of claim 9, wherein the conductive substrate has a larger surface area than the substrate. 12-20. (canceled) 